1. Field of the Invention
This invention relates to electricity and more particularly to an over heating detection circuit for disconnecting electrical power upon the detection of the over heated condition in an electrical plug.
2. Background of the Invention
The most common method of connecting an electrical appliance to an electric power source is through the use of an electrical power plug inserted into an electrical power source receptacle. The electrical power plug includes a first and a second electrical blade for insertion within a first and a second slot of the power source receptacle. The first and second electrical blades are retained within the first and second slots of the electrical power source receptacle by a resilient slot connector located within the first and second slots of the electrical power source receptacle. The resilient slot connectors located within the first and second slot provides a mechanical engagement between the resilient slot connectors and the inserted first and second electrical blades to enable a low resistance electrical contact therebetween.
In many cases, the mechanical and/or electrical contact between one of the resilient slot connectors and the inserted first and second electrical blades deteriorates thus raising the electrical resistance of the electrical contact therebetween. This deterioration of the mechanical and/or electrical contact between one of the resilient slot connectors and the inserted first and second electrical blades may be caused by a number of reasons.
The deterioration between one of the resilient slot connectors and the inserted electrical blade may be caused by corrosion of either the resilient slot connector and/or the inserted electrical blade. The corrosion of either the resilient slot connector and/or the inserted electrical blade results in an increase in electrical resistance therebetween. Furthermore, the deterioration between one of the resilient slot connectors and the inserted electrical blade may be caused by may be caused by a loss of resiliency of the resilient slot connectors. The loss of resiliency of the resilient slot connector reduces the mechanical contact between the resilient slot connector and the inserted electrical blade thus raising the electrical resistance of the electrical contact therebetween. In some instances, the mere aging of the electrical power plug and/or electrical power source receptacle may cause a loss of resiliency of the resilient slot connector as well as the corrosion of either the resilient slot connector and/or the inserted electrical blade.
The increase in resistance between the resilient slot connector and/or the inserted electrical blade results in an increase in heat during current conduction through the electrical contact between the resilient slot connector and the inserted electrical blade. The increase in heat further increases the resistance of the electrical contact between the resilient slot connector and the inserted electrical blade resulting in a progressive increase in heat and a progressive increase in electrical resistance. Ultimately, the progressive increase in heat will result in heat, smoking and possibly ignition of the electrical power source receptacle and/or the electrical power plug. Such an ignition may spread to adjacent areas causing loss of property and possibly the loss of life.
Therefore, it is an object of the present invention to provide an improved over heating detection circuit for disconnecting electrical power upon the detection of the over heated condition in an electrical plug.
Another object of this invention is to provide an improved over heating detection circuit cooperating with a disconnection circuit that is located within the electrical plug.
Another object of this invention is to provide an improved over heating detection circuit cooperating with a disconnection circuit located in a leakage current detector interrupter circuit (LCDI).
Another object of this invention is to provide an improved over heating detection circuit cooperating with a disconnection circuit located in a ground fault circuit interrupter (GFCI).
Another object of this invention is to provide an improved over heating detection circuit cooperating with a disconnection circuit that does not appreciably increase the cost to the disconnection circuit.
Another object of this invention is to provide an improved over heating detection circuit incorporated into a combined electrical plug and electrical socket for providing over heating detection protection for a conventional electrical plug.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by modifying the invention within the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.